For each year, it includes the highest number of people in space simultaneously during the year, and also the lowest number in space during the year. Sometimes it goes as high as 10 or more. The all-time high is 13 people in space simultaneously.

From the "Low" column, you can see that in fact space has had a human population continuously since 2001. During the years since then, the human population of space has never dipped lower than 2. So the period since 2001 really is the age of human habitation of space.

From the page linked above. (Except that the formating of the table doesn't work very well in a forum posting. I'll try to find a way to fix this and then edit the quote below)

THE POPULATION OF SPACE

At the time of this writing, February 11th, 2008, the population of space is ten.

Below is a history, year by year, of the population of space. Recent years are on top, earlier years are below. The column labeled RUS shows how many people went into space, during that year, aboard a Soviet/CIS/Russian launch vehicle. The column labeled USA shows how many went into space aboard an American launch vehicle. And the column labeled CHI is for the Chinese. TOT is the sum of the three. HI is the highest population in space at the same time during that year, and LOW is the lowest population during that year. This is based on space starting at 100 miles up, so the X-Prize winners, and X-15 flights are not included. The only suborbital flights that are included here are the first two Mercury flights and Soyuz 18-1.

The all time record is 13 people in space at once, and it has been tied several times. Often that number comes up when three people are on a space station, and three people are on a Soyuz, and seven people are on a Space Shuttle.

Hi Hitesh - I'm glad you made it into the forum after the earlier difficulties!

Thanks for the Virgin Galactic link. The main video on their website is absolutely superb, and their system of 'SpaceShipTwo' plus launch aircraft looks impressive. I note that on their site it says:"Book your place in space and join over 340 Virgin Galactic astronauts who will venture into space."

So how high will their flights go? If they will indeed count as spaceflights, then the "Total" figure for number of people in space in a given year will presumably climb into the hundreds after they've started their service.

100 kms and some change, enough to qualify as "space", though there should be an asterisk by the number as just "sub-orbital tourist flight".

The actual assent and free fall is a small part of the "experience" they are planning. You spend the better part of a week in a sort of abbreviated Space Camp, get a spiffy jumpsuit, some training classes, and then you go up in the carrier plane during another group's sub-orbital lift before your own to get a bit of a taste of high Gs and freefall.

For the amount of money these first customers are forking over, expecting a bit more than the usual airline "cram'em, fly'em, and dump'em" seems fair.

I have the hang of it now! Follow the link in my last post. Then underneath the graph, click the button that says "Collapse". Then move the slider to the right of that so that the graph zooms in on a smaller period of time such as (for instance) 2000 to the present. Then you can see clearly the human population of space sty any given time during that period. If you mouse over a particular day, you can see who was in space on that day. It is an absolutely awesome resource!

That graph was posted during 2014 and shows all human spaceflights up to that date.